1. Field of Invention
The present invention relates to an audio processing circuit and system, and more particularly to a POP noise suppression circuit having a simple structure, requiring no plug-in capacitor, and capable of suppressing POP noise, and a POP noise suppression system thereof.
2. Description of Related Arts
POP noise refers to noise that commonly exists in an audio system and is generated in a start-up or shutdown process.
In a start-up process of an audio system, an input and output voltage of the audio system during static operating is needed to be charged to a common-mode voltage; while in a shutdown process, the input and output voltage thereof is needed to be discharged to 0. Thus, in a start-up or shutdown process, a speaker or headphone driven by a driving terminal is easily to be impulsed to generate POP noise, which leads to discomfort of sensitive ears.
In the prior art, a plug-in capacitor of large capacitance is usually required to suppress POP noise, which increases the design cost in a large extent. Thus, it is necessary to provide a POP noise suppression circuit having a simple structure, requiring no plug-in capacitor, and capable of suppressing POP noise effectively, and a POP suppression system thereof.